Conventionally, through-away type cutting tools having excellent economical efficiency have been heavily used as cutting tools (for example, rotating tools) such as face mills and end mills. The cutting tool is formed by attaching a cutting insert to a holder.
The cutting insert having a long cutting edge is subjected to a large load at cutting. In order to reduce this load, for example, Unexamined Patent Publication No. 9-57519 discloses a cutting insert including a cutting edge located at an intersection between an upper surface and a side surface, and a groove formed on the side surface so as to divide the cutting edge. When the cutting insert is used for the cutting tool, a chip finely divided in the width direction is generated, so that cutting resistance applied to the cutting insert at cutting can be reduced. As the number of the grooves is increased, the length of each of the divided cutting edges becomes smaller and thus, the width of the chip also becomes smaller, thereby reducing the cutting resistance.
Since the narrow chips are easy to curl and discharged in an extended state, the chip tends to be clogged between the workpiece and the cutting edge. This configuration may disadvantageously cause damage of a worked surface of the workpiece and the cutting insert. Therefore, there has been a demand for a cutting insert that reduces the cutting resistance at cutting and has excellent chip discharging efficiency.